Various mobile devices, such as “smartphones,” watches, wearable devices, etc. are capable of running various application programs or “apps,” the Apple iPhone® series of devices being a common example. Other smartphones are currently made by Google, Microsoft, Samsung, LG and others. We refer to all such mobile devices, now known or later developed, as a “phone” in this document for simplicity. In many cases, apps are developed by third-party developers, meaning an entity or person that is not the manufacturer of the phone. A wide variety of apps are available for download to a phone, for example, from an app store. Application development for communication with an external accessory or device coupled to a phone (“EA”), has constraints which can make developing the software for communicating with the EA relatively costly and complex, due in some cases to limitations of inter-process communication protocols between the phone applications and how EA sessions are created and managed.